Photon counting LiDAR uses single photon detectors, which have extremely high detection sensitivity and can respond to a single photon signal, has become the development trend of LiDAR detection technology. However, the extremely high detection sensitivity makes it easy for single photon detectors of LiDAR systems to be interfered by background noise photons during the detection process. In addition, due to the limitations of various detection mechanisms of single photon detectors, there will be a certain dead time, which will have certain impact on the detection probability of single photon detectors. PMT and GM-APD are two basic types of photon detectors commonly used in photon counting LiDAR. In this paper, we compare the detection performance indicators of these two photon detectors from the principle of photon detection. The photo event response models of two kinds of detectors are summarized. The detection probability of the two kinds of detectors in photon counting LiDAR system under normal solar background noise is analyzed. The detection performance of the two kinds of photon detectors is compared, which can guide the subsequent design of photon counting LiDAR based on PMT and GM-APD detectors.